Smoke filter of fibrous material, especially for tobacco products



Sept. 18, 1956 A. MULLER' SMOKE FILTER OF FIBROUS MATERIAL, ESPECIALLY FOR TOBACCO PRODUCTS Filed NOV. 18, 1952 l i s224025 United States Patent() SMOKE FILTER OF FIBROUS MATERIAL, ESPE- CIALLY FOR TOBACCO PRODUCTS Paul'Adolf Mller, Rosenhugel, Herrliberg, Zurich, Switzerland Application November 18, 1952, Serial No. 321,118

Claims priority, application Switzerland November 27, 1951 11 Claims. (Cl. 131-208) My invention relates to smoke lters for use with tobacco products.

Attempts have been made since long ago to prevent noxious substances like nicotine, pyridine and ammonia from reaching the mouth of the smoker in harmful quantities by retaining them in smoke lters. The smoke filters now predominantly in use consist of a multi-layer strip of creped material folded in the longitudinal direction of the lter. The lter material consists, for instance, of creped multi-layer tissue paper or creped cellulose wool with or without intermediate layers of ltering or absorptive materials such as cotton tissue. These filters have distinct longitudinal passages through which the smoke may pass unobstructed and hence unltered. Consequently, the ltering is far from perfect. To cure this deciency it has been proposed to place a wad of cotton on the tobacco side of the lter for absorbing the noxious substances ahead of the lter proper. However, such a lter combination also fails to fully solve the problem, aside from being complicated and hence expensive to manufacture.

Various other lter inserts, made of sponge, wool, wood or masses produced from lter paper, have failed to nd Y,

acceptance either because they were technologically unsatisfactory for ltering or because they were too expensive or could not readily be joined with the tobacco products, for instance, cigarettes.

The additional use of absorbent substances such as activated charcoal also failed to bring satisfactory results as the, absorbent substances are partly loosened during smoking and inhaled together with the noxious substances.

According to another proposal, disclosed in my copending application Serial No. 284,860, led April 29, 1952, smoke lter bodies are made from dried wood cellulose pulp with a promiscuous ber orientation so that there are no through passages in the longitudinal direction of the lter body. While such lters have good ltering qualities, they are not entirely satisfactory because, when using only wood cellulose ber pulp, the permeability of the lter is generally too slight. It is therefore necessary to increase the permeability to an acceptable measure by applying particular manufacturing expedients which, however, also increase the cost of the lter body.

My present invention has for its object to provide a lter body which o'ers all advantages of the last-mentioned type of lters but avoids its disadvantages.

According to my invention, a smoke lter consists of brous material arranged in strata of alternately larger and smaller density respectively which are felted together to form a coherent lter body. These strata, or at least one or several of the denser strata, extend continuously across the entire cross section of the lter body, and the bers within the material of the strata have irregular directions so that there is no preferred ber orientation. Consequently, there is no continuous strand of fibers or passage in the longitudinal direction of the lter body.

Patented Sept. 18, 1956 The individual strata of ber material are generally parallel and extend perpendicularly or slanted to the longitudinal direction of the filter body. For some purposes it is preferable to give the denser strata dierent thicknesses, for instance, in such a manner that the denser strata in the middle portion of the lter body are thicker than those near the ends, or vice versa. Furthermore, the strata of ber material may be disc shaped or cone shaped, the cone axis in the latter case extending in the longitudinal direction of the lter body. Within the same lter body the strata may have all about the same shape, or their shapes may be different. For instance, at one end of the lter body the strata may have the shape of a at disc perpendicular to the lter axis, while gradually changing into conical shape toward the other lend of the body, the cone axes extending generally lengthwise of the lter body.

Advantageously used as ber material is a cellulose ber material, particularly wood cellulose ber material. However, for loosening the ber texture, other cellulose bers may be added to the wood cellulose ber material. It is then preferable to limit the quantity of such additions to at most 50% by Weight of the entire ber material. Suitable as such additions are especially cotton bers and/ or wood bers. Suitable as ber materials, particularly as additions to a wood cellulose ber material, are also brous substances of inorganic, for instance mineral character, such as asbestos bers, or articial materials such as nylon. v

The drawing shows by way of example several embodiments of smoke lters according to the invention. Fig. l illustrates schematically and on an enlarged scale av longitudinal section through part of a stratied lter body, while Figs. 2 to 9 show schematically and in-section eight different modications respectively.

According to Fig. l, the lter body 11 is composed of strata 12 of ber material felted together by strata 13 of lesser density so that the stra-ta 12 are distinctly perceptible. Within and between the strata 12 the bers are promiscuously distributed, that is they have no preferred orientation so that there is no continuous ber strand in the longitudinal direction of the lter body.

Various kinds of arrangement and shape of the ber strata within a lter body, for instance, of the length L, are apparent from Figs. 2 to 9. The lter body according to Fig. 2 consists of at disc-shaped strata 12 of ber material parallel to each other and perpendicular to the longitudinal direction of the lter body. Thelayers are felted together at 13 by strata of lesser density and are thus joined together to a coherent unit.

The lter body according to Fig. 3 has brous strata 12 which are about shell shaped, having a bulge in rough approximation to a cone. The conical shape is more clearly apparent in the embodiment of Fig. 4. The cone axes :of the strata extend longitudinally of the lter body but these axes need not coincide with the longitudinal center axis of the lter body.

A more pronounced conical shape is apparent from the brous strata inthe lter according to Fig. 6. In thisV variations and indicate especially (as is also apparent` from Figs. 3, 4, k6, and 7) that the strata have irregular or .wavy surface zones. ln connection with the embodiments of Figs. 8 `and 9 it will be noted that the axes of the generallyconical strata run generally lengthwise of the lter body but do not coincide with the longitudinal axis ofthe body. Indeed, it is also unnecessary to have the cone axes of the strata extend parallel to the longitudinal axis of the filter body.

In all illustrated embodiments the fibrous strata 12 and the intermediately located fibers serving to establish coherence of the strata 12, consist preferably of cellulose fibers, particularly fibers of wood cellulose. Depending upon the particular use of the smoke filter body, its length and its `diameter other cellulose fibers may be added to the Wood-cellulose fiber material, for instance cotton fibers and/or wood fibers, for the purpose of loosening the texture. The described smoke filter bodies are substantially free of through passages and through-going fiber strands parallel to the filter axis thus securing good and uniform smoke-filtering qualities. These filters are also advantageous as regards manufacturing requirements and cost, because each filter body consists of a single mass, in contrast to many known filters that are composedv of different materials whose assembly increases the cost of the manufacturing process and hence of the product.

One of the manufacturing methods for producing the above-described filters is as follows. A wet pulpy mass of the fibrous material, well mixed or vibrated to secure a promiscuous fiber orientation, is drained from a container through a waterpermeable tubular structure, and sufficient pressure is applied to the structure to eliminate much of the water from the pulp. As a result, a strand or sliver is issued. This sliver is subjected to drying and shaping under application of a periodically varying pressure to produce alternately dense and loose strata that remain coherent. A process and machinery applicable for the production of such filters is described in my copending application Serial No. 366,316, filed July 6, 1953. However, it will be understood that the particular manufacturing method is not essential to the present invention and that other methods suitable to stratify the filter may also be used.

I claim:

1. A tobacco smoke filter for smoking articles, comprising a multiplicity of discernible strata extending transverse to the filter axis and consisting all of the same filter material, said strata having alternately larger andsmaller densities respectively, said filter material in each of said strata consisting of a mass of individual, promiscuously oriented fibers and having substantially the same density throughout said mass, said respective strata being felted together and forming together a coherent filter body, at least one of said strata of larger densityextending continuously over the entire cross section of the filter body so that said body is free of any through passages parallel to the filter axis.

2. A tobacco smoke filter for smoking articles, comprising a multiplicity of discernible strata all extending substantially parallel to one another over the entire cross section of the filter in a direction transverse to the filter axis and all consisting of the same filter material, said strata having alternately larger and smaller densities respectively, said filter material in each of said strata consisting of a mass of individual fibers promiscuously oriented to exclude through passages parallel to the filter axis, said mass having substantially uniform density throughout each individual stratum, and said respective strata being felted together and forming together a coherent filter body. y

3. A tobacco smoke filter for smoking articles cornprising a multiplicity of discernible strata all extending substantially parallel to one another over the entire cross section of the filter in a direction slanted, at least in part, with respect to the filter axis, said strata consisting all of the s'ame filter material and having alternately larger and smaller density respectively, said filter material in each of said strata consisting of a mass of individual fibers promiscuously oriented to exclude through passages parallel to the filter axis, said mass having substantially uni- 4 form density throughout each individual stratum, and said respective strata being felted together and forming together a coherent filter body.

4. ln a tobacco smoke filter according to claim 2, said filter body having an axially elongated cylindrical shape of a flat disc and extending substantially perpendicularly to the filter axis.

5. A tobacco smoke filter for smoking articles, comprising a multiplicity of discernible strata all extending substantially parallel to one another over the entire cross section of the filter in a direction transverse to the filter axis, each of said strata having the shape generally of a hollow cone with the cone axis parallel to the filter axis, said strata consisting all of the same filter material and having alternately larger and smaller density respectively, said filter material in each of said strata consisting of a mass of individual fibers promiscuously oriented to exclude through passages parallel to the filter axis, and said respective strata being felted together and forming together a coherent filter body.

6. A tobacco smoke filter for smoking articles cornprising a multiplicity of distinct strata all of the same fibrous material, said strata having alternately different densities respectively and being felted together to form a coherent filter body, and said strata extending substantially over the entire cross section of the filter body, said fibrous material in each stratum consisting of a mass of individual fibers promiscuously oriented throughout the stratum, and different strata having respectively different shapes.

7. In a smoke filter according to claim 6, said filter body having elongated cylindrical shape, the strata at one axial end of said filter body having substantially fiat shape and extending perpendicularly to the longitudinal axis of the body, and the other strata having a shape gradually varying into cone shape toward the other end of the body, the cone axis extending approximately lengthwise relative to the body.

8. A tobacco smoke filter for smoking articles, comprising a multiplicity of discernible strata extending transverse to the filter axis and consisting all of the same filter material, said strata having alternately larger and smaller densities respectively, and said strata of larger density being axially thicker than said strata of smaller density, said filter material in each of said strata consisting of a mass of individual promiscuously oriented fibers and having substantially the same density throughout said mass, said respective strata being felted together and forming together a coherent filter body of substantially cylindrical, elongated shape, and said strata extending continuously over the entire cross sectiony of the filter body.

9. A tobacco smoke filter for smoking articles, comprising a multiplicity of discernible strata all extending substantially parallel to one another over the entire cross section of the filter `in a direction transverse to the filter axis and all consisting of the same filter material, said strata having alternately larger and smaller densities respectively, said filter material in each of said strata consisting of a mass of individual organic fibers interlaced and promiscuously oriented, said mass having substantially uniform density throughout, and said strata being mutually interfelted and forming together a coherent filter body.

l0. In a tobacco smoke filter according to claim 9, said fibers in'all said strata consisting of wood-cellulose fibers.

1l. In a tobacco smoke filter according to claim 9, said fibers in all said strata consisting of a mixture of woodcellulose fibers and other cellulose fibers amounting up to about one-half by weight of the total mixture.

(References on following page) 5 References Cited n the tile of this patent 1,862,659 P 2,521,985 UNI'1`ED STATES ATENTS 2,5 8 619 3 5 956,832 SeltZ May 3, 1910 1,411,975 Matson Apr. 4, 1922 1,807,521 P01111( May 26, 1931 166,614

6 Christofferson June 4, 1932 Lang et a1 Sept. 12, 1950 Gerson Feb. 26, 1952 FOREIGN PATENTS Germany Ian. 13, 1906 

